<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Yy</title>
    <script src="./js/vue.js"></script>
</head>

<body>
    <div id="app">
        <button @click="jian">-</button>
        <span>{{count}}</span>
        <button @click="jia">+</button>

    </div>
    <script>
        new Vue({
            data: {
                count: 0
            },
            methods: {
                jian() {
                    this.count--
                },
                jia() {
                    this.count++
                },

            }
        }).$mount("#app")
    </script>
</body>

</html>